Sheet-handling apparatus

ABSTRACT

The sheet-handling apparatus has a stacking device which includes a vertically movable hoist that indexes downward as the sheets are deposited thereon. A sheet bunk is positioned on the hoist having sides that extend outward beyond the edges of the hoist. An elongated reciprocable carriage is mounted circumscribing the hoist with one end adjacent the hoist to receive a loaded bunk thereon as the hoist descends below the top of the carriage. The carriage is then reciprocated to remove the loaded bunk from the stacking device and move the other end adjacent the hoist to position an empty bunk on the hoist.

United States Patent Hayes 1 Feb. 15, 1972 [s41 SHEET-HANDLING APPARATUS 2,869,739 1/1959 Davis ..2 14/164 R inventor: Leonard L y Lewiston, 1d aho 3,390,508 7/1968 Helmhcher ..214/6 DK X [73] Assignee: Potlatch Forests, Inc., Lewiston, Idaho Prim y n ra|d M- Forlenza I Assistant Examiner-Robert]. Spar [221 Flled- Attorney-Wells, St. John & Roberts 21 A 1. No.1 5 609 l 1 pp 57 ABSTRACT v 52 U.S. Cl. ..2l4/6 H, 271/88 The Sheet-handling apparatus has a Stacking device which 51 1 Int. Cl ..B65g 57/02 dudes vertically Hm/able mist that indexes dmvnward as [53] Field of Search 271/88. 214/6 6 A 6 K 6 H sheets are deposited thereon. A sheet bunk is positioned on 21476 P 6 i the hoist having sides that extend outward beyond the edges of the hoist. An elongated reciprocable carriage is mounted cirf cumscribing the hoist with one end adjacent the hoist to [56] Re erences Cited receive a loaded bunk thereon as the hoist descends below the UNITED STATES PATENTS top of the carriage. The carriage is then reciprocated to remove the loaded bunk from the stacking device and move 2,423,557 7/1947 Gray ..214/16.4 X the other end adjacent the hoist to position an empty bunk on 2,698,692 l/l955 Jones et al ..214/6 DK the hoist 2,765,599 10/1956 Johnson ....214/6 H X 2,849,236 8/1958 Beaulieu ..2l4/6 H X 2 Claims, 9 Drawing Figures PATENTEUFEBIS I972 3542.151

SHEET 1 0F 4 INVENTOR.

Leonard L. Hayes BY :QH-ys PAIENTEUFEB 15 me saw 3 0r 4 INVENTOR.

M w a 1...... H Mow L...R A. I Lw This invention relates to sheet-handling equipment and more particularly to equipment for stacking sheets and efficiently conveying the sheet stacks from the stacking equipment.

One of the basic problems found in developing high-capacity sheet handling and stacking equipment is the inability to provide an efficient and reliable means for removing the stacks from the stacking equipment once the stacks are formed. Frequently the stack removal apparatus is the limiting element thereby defining the capacity of the equipment. This has been particularly true in the plywood industry, especially in handling and stacking green veneer.

In the production of plywood, frequently ribbons of wood veneer are peeled from the logs and conveyed past a chopper that cuts the ribbons into sheets of various sizes while deleting sections having unwanted defects.

The sheets are formed in stacks and moved from the stacking equipment for further processing. Frequently forklift trucks are used to remove the formed stacks from the stacking equipment and transfer the stacks to another location.

Applicants U.S. patent application Ser. No. 871,478 titled Sheet Conveying and Stacking Apparatus" describes equipment for conveying plywood veneers to a plurality of stacking stations and forming the sheets into stacks that can be easily carried to other parts of a plywood plant for further processing in the formation of plywood. Although such equipment performs exceptionally well, the sheet-handling capacity of the equipment is restricted by the lack of an efficient and reliable means of removing the stack from the equipment after the stack is formed.

One of the principal objects of this invention is to provide a novel means of servicing sheet-stacking equipment to efficiently and reliably remove formed stacks from the stacking equipment without unduly interrupting the stacking operatron.

An additional object of this invention is to provide stackhandling equipment that is inexpensive to manufacture and maintain.

A further object of this invention is to provide sheet-handling equipment having a stack-handling apparatus that does not lift the formed stack from the stack equipment during the removal process.

An additional object of this invention is to provide an inexpensive and efficient apparatus for removing sheet stacks from the sheet handling and stacking equipment described in U.S. patent application Ser. No. 871,478, now U.S. Pat. No. 3,622,150, issued Nov. 23,1971.

These and other objects and advantages of this invention will become apparent upon the reading of the following detailed description ofa preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of this invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a plan view of sheet-handling apparatus showing means for conveying veneer sheets to various stacking stations and then stacking the sheets in stacks; and means for removing the stacks from the stacking stations;

FIG. 2 is a side elevational view of the sheet-handling apparatus illustrated in FIG. 1;

FIG. 3 is a vertical cross sectional view taken along line 3 3 in FIG. 1 showing in more detail a stacking station in conjunction with stack-handling equipment for removing the stacks from the stacking station, said stack-handling equipment having a movable carriage with stack bunks associated therewith;

FIG. 4 is an isolated plan view of the carriage illustrated in FIG. 3;

FIG. 5 is a side view of the carriage illustrated in FIG. 4;

FIG. 6 is an end view of said carriage;

FIG. 7 is an isolated end view ofa bunk shown in FIG. 3;

FIG. 8 is an isolated plan view of said bunk; and FIG. 9 is a side view ofsaid bunk.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Now referring in detail to the drawings, there is shown in FIG. 1 a sheet-handling apparatus 10 designed specifically for handling veneer sheets 11. The sheet-handling apparatus 10 includes an elongated sheet conveyor 12 that moves the sheets to stack-forming stations 13, 14, and 15 that are longitudinally spaced along the conveyor. The conveyor 12 moves the sheets crosswise in an arched condition with the grain of the veneers perpendicular to the direction of movement.

The sheet-handling apparatus 10 includes a sheet-stacking device 17 at each of the stack forming stations 13, 14, and 15. Associated with each sheet-stacking device 17 is a stack-handling device 18 for removing formed stacks from the sheetstacking device and moving the stacks alternately to stack discharge stations 20 and 21 that are located on opposite sides of stack-forming stations transversely spaced from the sheet conveyor 12.

More specifically, the sheet conveyor 12 has a frame 23 (FIG. 2) with two transversely spaced longitudinal belts 24 and 25 movably mounted on the frame between idler pulleys 26 and drive pulleys 27 respectively to present belt surfaces that are substantially upright at an inclined angle (see FIG. 3) to engage and support the ends of the veneer sheets and conveying the veneer sheets in an arched condition along the sheet conveyor to one of the stack forming stations 13, 14, or 15. Guide bars 30 and 31 are mounted on the frame 23 adjacent to the conveying surfaces of the belts 24 and 25 respectively for guiding the sheets as the sheets are moved by the belts to desired stacking stations.

Each of the sheet-stacking devices 17 includes two ejector elements 33 and 34 (FIG. 3) that are mounted on the opposite sides of the sheet conveyor for ejecting the sheets from the sheet conveyor at desired stack-forming stations. The ejectors 33 and 34 are operated by hydraulic cylinders 35 and 36 respectively for moving ejector elements inward and downward to remove theends of the arched sheet from the belts and to discharge the sheets from the sheet conveyor at the respective stack-forming station. Each of the sheetstacking devices 17 also includes a hoist or scissor lift 38 that is stationarily mounted for receiving the sheets and indexing the sheets downwardly to deposit a formed stack on the stackhandling device 18 associated therewith. The scissor lift 38 includes a base 40 stationarily affixed to the ground. Scissor legs 42 and 43 are pivotally mounted between the base and a vertically movable platform 41. A scissor lift hydraulic cylinder 44 is utilized to raise the platform to a position immediately below the sheet conveyor 12 and then index the platform downward as sheets are added to the platform. The cylinder 44 lowers the platform below the level of the stack-handling device 18 to deposit the formed stack thereon. More specific details of the conveyor 12 and the stacking device 17 are disclosed in the applicant's copending application Ser. No. 871,478, now U.S. Pat. No. 3,622,159 issued Nov. 23, I971.

The stack-handling device 18 includes a mobile carriage 45 that is mounted on rails 46 and 47 that extend between the stack-handling stations and their respective stack discharge stations 20 and 21. Each carriage 45 has wheels 48 that movably support the carriage on the rails 46 and 47. The carriage 45 has a rectangular frame 50 (FIG. 4) with two parallel side members 51 and 52 that are interconnected at their ends by end members 53 and 54 forming a central rectangular opening 55 which accommodates the scissor lift 38. The side members 51 and 52 move alongside the lift 38 when the carriage is reciprocated.

The carriage 45 has a stack location 58 at one end thereof and a stack location 59 at the other end thereof for receiving the stacks and moving the stacks alternatively to the stack discharge stations 20 and 21.

The stack-handling device 18 further includes a sheet bunk 60 that is normally supported on the carriage at stack location 58 and a sheet bunk 61 that is normally supported on the carriage 45 at the stack location 9. Each of the sheet bunks 60 and 61 includes a rectangular frame 62 (FIGS. 79) having upper crossmember 63. The crossmembers 63 have a concave upper surface 64 (FIG. 7) for bowing the sheets slightly as the sheets are formed into a stack. Bottom flanges 66 (FIG. 7) are mounted along the bottom of the bunks at space locations to fit conveniently on the carriage 45 to prevent the bunks from moving or sliding off the carriage.

The stack-handling device 18 includes a carriage drive means 70 (FIG. 1 and 3) having a chain 71 attached or extending between the end members 53 and 54. The chain 71 extends over an idler sprocket 72, idler sprocket 73, and a drive sprocket 74. The idler sprockets 72 and 73 and the drive sprocket 74 are rotatably mounted on the fixed base 40. The drive sprocket 74 is operatively connected to a motor 75 through a reduction box 76. The motor 75 is reversible for driving the carriage in either direction in the reciprocating manner to alternately position the stack locations 58 and 59 at the stack-forming station to remove a sheet bunk that has been loaded with a stack of sheets from the stack-forming station and feeding the other emptied bunk to the stack-forming station.

During the operation of the sheet-handling equipment, veneer sheets are fed to the sheet conveyor 12 sideways in an arched condition with the grain of the veneer transversely to the longitudinal axis of the sheet conveyor. The belts 24 and 25 in conjunction with the guide rods and 31 convey the sheets to one of the stack-forming stations 13, 14, or 15. Generally the sheets of approximately the same width are stacked at the same statiomThe number of stations can be increased or decreased depending upon the number of different sized sheets that are required to be stacked. As a sheet approaches the desired station, the ejectors 33 and 34 are operated to discharge the sheet downwardly onto the sheet bunk 60 which has been positioned on the scissor lift platform 41 at the elevated position (FIG. 3). As additional sheets are dropped or ejected onto the sheet bunk, the hydraulic cylinder 44 indexes the bunk dow nwardly as each sheet is added. When a full load is formed, the cylinder lowersv the platform 41 below the top of the carriage 45 depositing the sheet bunk 60 at the stack position 57 on the carriage 45. The operator then initiates the operation of the motor 75 to drive the carriage in the opposite direction to remove the loaded sheet bunk 60 from the stack-forming station 13 and move said loaded bunk to the stack discharge station 20. At the same time the empty sheet bunk 61 is moved from the stack discharge station 21 to the stack forming station 13 immediately above the lowered platform 41. The scissor lift 38 is then operated to move the platform upwardly through the rectangular space 55 to raise the sheet bunk 61 to a position immediately below the sheet conveyor 12 to receive additional sheets in the formation ofa second stack. The stack on the sheet bunk 60 and positioned at the stack discharge station 20 is removed by means such as a fork to empty the sheet bunk 60 while sheet bunk 61 is receiving sheets.

The process is repeated with the carriage moving in the opposite direction to position the stack formed on the bunk 61 at the discharge station 21. The use of the stack-handling device 18 nearly doubles the sheet-handling capacity of the equipment 10.

It should be understood that the above-described embodiment is simply illustrative of the principles of this invention and numerous other embodiments may be readily devised by those skilled in the art which incorporate the principles of this invention. Therefore, only the following claims are intended to define this invention.

What is claimed is:

1. A sheet-handling apparatus for arranging sheets in stacks at a stack-forming station and moving the formed stacks to stack discharge stations on opposite sides of the stack-forming station, comprisin a. a reciprocaifiy movable carriage having two adjacent stack support locations in which one location moves between one stack discharge station and the stack-forming station and the other location alternately moves between the stack-forming station and the other stack discharge station as the carriage is reciprocated;

b. a first stack bunk normally supported on the carriage at said one stack support location;

c. a second stack bunk normally supported on the carriage at said other location;

. a vertically movable hoist located at the stack-forming station for moving upward to remove one of the stack bunks from the carriage and carry the bunk to an elevated position to receive sheets thereon and to move downward as sheets are deposited on the bunk to place a loaded bunk on the carriage;

e. means at the stack-forming station for depositing sheets on the bunk supported on the hoist to form a stack;

f. carriage drive means operatively connected to the carriage for reciprocating the carriage to alternate the movement of the first and second stack bunks to and from the stack-forming station to move stacks placed thereon to the discharge stations; and

g. said carriage having a frame encircling the vertically movable hoist with an elongated central opening formed therein extending unobstructed between the ends of the carriage with the hoist confined within the elongated opening for vertical motion and with the bunks supported over the elongated opening to enable the hoist to move unobstructed by the carriage frame upward and downward through the central opening to raise and lower 7 the bunks respectively to and from the stack support locations.

2. A sheet-handling apparatus as defined in claim 1 wherein the carriage frame is rectangular with two spaced parallel side members interconnected by two end members with the side members moving alongside the hoist as the carriage is reciprocated. 

1. A sheet-handling apparatus for arranging sheets in stacks at a stack-forming station and moving the formed stacks to stack discharge stations on opposite sides of the stack-forming station, comprising: a. a reciprocably movable carriage having two adjacent stack support locations in which one location moves between one stack discharge station and the stack-forming station and the other location alternately moves between the stack-forming station and the other stack discharge station as the carriage is reciprocated; b. a first stack bunk normally supported on the carriage at said one stack support location; c. a second stack bunk normally supported on the carriage at said other location; d. a vertically movable hoist located at the stack-forming station for moving upward to remove one of the stack bunks from the carriage and carry the bunk to an elevated position to receive sheets thereon and to move downward as sheets are deposited on the bunk to place a loaded bunk on the carriage; e. means at the stack-forming station for depositing sheets on the bunk supported on the hoist to form a stack; f. carriage drive means operatively connected to the carriage for reciprocating the carriage to alternate the movement of the first and second stack bunks to and from the stack-forming station to move stacks placed thereon to the discharge stations; and g. said carriage having a frame encircling the vertically movable hoist with an elongated central opening formed therein extending unobstructed between the ends of the carriage with the hoist confined within the elongated opening for vertical motion and with the bunks supported over the elongated opening to enable the hoist to move unobstructed by the carriage frame upward and downward through the central opening to raise and lower the bunks respectively to and from the stack support locations.
 2. A sheet-handling apparatus as defined in claim 1 wherein the carriage frame is rectangular with two spaced parallel side members interconnected by two end members with the side members moving alongside the hoist as the carriage is reciprocated. 